Lots of these services require you to confirm that you can actually be reached through an email address that you provide, before you can use them. As a result quite a few people have taken to create a separate email account just for these registration purposes. It's one of the ways to combat the amount of emails that you get in your inbox and minimize the risk of appearing on someone's spam list.
Problem with this approach is that now you have TWO accounts that you have to use and check. At least when you need to check for confirmation emails or maybe when you need to recover passwords that you forget.
Well, with Gmail, there is a way to have a single account but at the same time have virtually unlimited amount of email addresses associated with it. Actually there are two such ways :-D
D.ot.s a.re (semi)imp.ort.ant
If you're like me, then you created your Gmail account in email@example.com format. Some people do it in firstname.lastname@example.org format. Or you use whatever other type of account name you like. Doesn't really matter. What matters is that Google will deliver emails to your account even if punctuation is different than what you specified as your username. So, if your default email address is email@example.com then also emails to firstname.lastname@example.org will reach you. As well as email@example.com or firstname.lastname@example.org or email@example.com or any other combination in between.
Neat, eh? :-)
You probably know that Google is doing its best to compete with Facebook, with Google+ service, for the status of social network king. If it will succeed or not remains to be seen. But it seems (may be a coincindence) that a bit of that "plussiness" has spilled over to Gmail.
It seems like that, because another way to generate additional email addresses is to add + sign at the end of your username and follow it with a string of characters. For instance firstname.lastname@example.org Or email@example.com
Of course you could combine this with the first technique but that would likely complicate things a bit.
How does this help me?Well, one of the things that you can fairly effectively do in Gmail is creating filters for your incoming emails. The thing is that if you wanted to create a filter for every loyalty program, forum or newsletter, and you weren't using either of the above tricks, then you had to create a lot of individual filters that were based on sender addresses. And additional problem was that, relatively often, sender addresses change. Which means that it can happen that one of your filters stops working all of a sudden and you may have a hard time figuring out why.
With firstname.lastname@example.org you just need to create a filter that will rely on your receiving email. And it can be one filter for all loyalty programs for which you registered with that particular address. If sender address changes at any time in the future or if your registration email is provided to some third-party company, then all the extra correspondence will be automatically treated with the same loyalty filter and will not clutter your inbox. Plus (hehe) you will have a better overview in regards with how your email information circulates around the internet.
What this nifty feature will not do?
Email addresses (more properly called aliases, for those of you that are detail nazis) generated like this are for receiving emails only. You will not be able to use them for outgoing emails. Any mail that you send will still be sent under your original email@example.com
Also, the login name (what you type in combination with your password when you login to Google services) can only be your original username, that you picked when you subscribed for a Google account.